The objectives of this study are to reclassify selected brain tumors in children so that each site-specific tumor subtype is as homogeneous as possible in regard to prognosis, and hopefully in regard to etiology, and to identify risk factors of selected site-specific childhood brain tumor subtypes of uniform prognosis. With the aid of each participating registry, permission will be sought from all concerned to obtain slides of each brain tumor and data about each child with a brain tumor identified between 1/1/78 and 12/31/82. Slides will be reviewed by 2 neuropathologists simultaneously, who will complete a standardized data sheet. Observer variability will be assessed. The hospital record will be reviewed and a standardized data sheet completed. The parents of each child will be interviewed in their own home with a standardized questionnaire, as will the parents of the children who will serve as controls. The data collected with the assistance of participating registries will be pooled with comparable data obtained from a consortium of major pediatric neurosurgery referral centers (located outside the geographic bounds of the SEER registries) for the analyses that are planned for after the completion of this grant. (RB)